Dennostein 3D is a mod for shareware Wolfenstein, made by Denno.
No new levels are featured. The guards have been replaced by Homer Simpson who always goes D'oh! when he is shot. Other than Homer's face, none of the new wall textures have much to do with The Simpsons.
Initially released on the Dome in March 2004, it was found in a market by David O'Rafferty. Though released as Simpson's Doom, the download contains a Read Me file where it is disclosed that it is in fact titled Dennostein 3D, and that it is version 2.1. Previous versions were obviously made, but none have surfaced.
Version 2.1's VSWAP dates from June 1995.
Originally made for shareware Wolfenstein v1.2.